18766221 has 8 divisors (see below), whose sum is σ = 25042080. Its totient is φ = 12500592.

The previous prime is 18766211. The next prime is 18766303. The reversal of 18766221 is 12266781.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 18766221 - 2⁶ = 18766157 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18766201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4546 + ... + 7628.

It is an arithmetic number, because the mean of its divisors is an integer number (3130260).

Almost surely, 2^18766221 is an apocalyptic number.

It is an amenable number.

18766221 is a deficient number, since it is larger than the sum of its proper divisors (6275859).

18766221 is a wasteful number, since it uses less digits than its factorization.

18766221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5115.

The product of its digits is 8064, while the sum is 33.

The square root of 18766221 is about 4331.9996537396. Note that the first 3 decimals coincide. The cubic root of 18766221 is about 265.7412308123.

The spelling of 18766221 in words is "eighteen million, seven hundred sixty-six thousand, two hundred twenty-one".